WO 2005/066488 describes a so-called laser ignition. This laser ignition includes an ignition laser protruding into the combustion chamber of an internal combustion engine. This ignition laser is connected via a light guide device to a pumped light source.
A so-called combustion chamber window, which is transmissive for the laser pulses generated in the ignition laser, is present on one end of the ignition laser facing the combustion chamber. The laser wavelength is between 500 nm and 1500 nm, preferably between 900 nm and 1100 nm. This combustion chamber window must be accommodated in a housing of the ignition laser with a seal. High demands are made of the seal between the combustion chamber window and the housing because surface temperatures of more than 600° C. may occur on the combustion chamber window during operation in an internal combustion engine, for example. In addition, intermittent pressure loads of more than 250 bar also occur. When an ignition laser is used to ignite a gas turbine, lower pressures prevail in the combustion chamber of the gas turbine but the surface of the combustion chamber window may reach temperatures of up to 1000° C.
It is apparent that the interior of the ignition laser must be sealed with respect to the extremely high temperatures and pressures prevailing in the combustion chamber. In other words, if exhaust gases went from the combustion chamber into the interior of the ignition laser, this would lead to failure of the ignition laser.